Permalink configuration for custom pages

I need to accept url variables in one of my theme’s template files. If I currently have https://domain.com/page/?do=subscribe&id=93, I need it to rewrite to https://domain.com/page/subscribe/93. In this case it will probably only be one variable (no ID), but I’d like to account for both possibilities. I’ve been reading through WP permalink hooks & functions but I’m still unsure of how and where to correctly implement them.

Any input is appreciated!